Reciprocating flitch tables for use with veneer slicers are known. Such flitch tables hold a flitch and move relative to a slicing knife. As the flitch passes the knife, the knife slices a sheet of veneer from the flitch.
Conventional flitch tables use a plurality of dogs to hold the flitch in position against a mounting surface of the flitch table. The dogs are clamping members that extend from the mounting surface of the flitch table and are positioned on either side of the flitch along the flitch table. Typically, the dogs include a sharp-edged portion oriented parallel to the mounting surface of the flitch table to cut into the flitch and hold it in place against the flitch table. The dogs are moved toward each other to pinch the flitch therebetween.
An alternative dogging arrangement is disclosed in U.S. Pat. No. 5,150,746 to Weil. Weil discloses a plurality of oval-shaped rotating dogs that include a sharp-edged portion at the ends of the major axis of the oval. The dogs are arranged in parallel rows along the mounting surface of the flitch table. A plurality of axially extending grooves are cut into the mounting surface of the flitch. The grooves are cut to align with the rows of dogs and are sized to allow the dogs to fit up into the grooves when the major axis of the oval is aligned with the groove. When the flitch is mounted on the flitch table, the oval-shaped dogs extend upwardly into the grooves and are rotated to engage the sharp-edged portion of the dogs with the flitch.
Regardless of whether clamping dogs or rotating dogs are used, conventional flitch mounting techniques require that the flitch mounting surface be positioned adjacent the flitch table mounting surface. Unfortunately, these conventional mounting techniques cause some veneer on a log to be wasted. In particular, conventional dogs extend about ⅝ inch from the mounting surface of the flitch table. In order to avoid contact between the slicing knife and the dogs, the slicer must stop slicing as the knife approaches the dogs, thereby leaving a considerable amount of veneer as waste on the backing board. Also, the grooves cut in the flitch to receive the dogs remove enough wood from the flitch so as to provide a weakened area that allows the flitch to flex under pressure from the knife. The flexing of the flitch produces shim sheets that are unusable and hence waste.
When a flitch is to be sliced on a reciprocating slicer, it is typically squared off to remove most, if not all, of the natural taper of the log. The flitch is then cut down the middle along its longitudinal axis so that the plane formed by the cut defines a flitch mounting surface. Typically, the flitch is mounted with the flitch mounting surface positioned adjacent the flitch table and held in place by conventional dogs. Of course, as the veneer is sliced from the flitch, the thickness of the flitch is reduced until the dogs approach the plane of travel of the knife. In addition, the grooves cut in the flitch mounting surface result in shim sheets, thereby placing another limit on how much veneer can be removed from the flitch. Thus, there is a limit to how much veneer can be removed from a flitch in order to avoid contact between the knife and the dogs and/or to avoid shim sheets. In conventional flitch tables, the remaining flitch, or backing board, is typically on the order of 1 to 1½ inches thick. If the remaining thickness of the backing board can be reduced, a veneer producer can achieve greater productivity from the same flitch.
When a flitch is to be sliced on a rotary veneer slicer, it is typically cut in half along the longitudinal axis of the flitch and the naturally occurring taper is retained. The plane of the cut forms the flitch mounting surface which is positioned against the mounting surface of a rotary staylog. Because the tree trunk is naturally tapered, one end of the flitch is thicker than the other end, and consequently extends a greater distance from the mounting surface of the staylog. As a result, the veneer-producing zone of the flitch is frusto-conical, i.e., trapezoidal in cross-section when viewed from the side of the flitch or from the knife. As the staylog and the flitch are rotated in a rotary veneer slicer, the knife first encounters the thickest portion of the flitch. With each rotation, the knife slices a wider veneer sheet until the entire length of the flitch is exposed to the knife. Once the entire length of the flitch is being sliced, subsequent sheets are of substantially uniform width. However, the initial sheets, which are cut from the best part of the log, are too narrow to be useful, and are thrown away as wasted product. Consequently, some of the best veneer on a flitch is thrown away as waste. In addition, with the prior art methods of retention, the grooves formed along the length of the flitch remove sufficient material from the flitch that the flitch loses its rigidity and flexes in response to the pressure of the slicing knife resulting in, at best, nonuniform and unacceptable slices of veneer.
A tapered flitch can also be sliced on a reciprocating flitch table, but the same problem exists. That is, the taper of the flitch will prevent the first sheets sliced from the flitch from being used, even though the first sheets come from the best portion of the flitch. Moreover, the grooves cut in the flitch to receive the dogs result in a weakened area that allows the flitch to flex under pressure of the knife. Regardless of whether the flitch is sliced on a rotary or reciprocating slicer, the flitch would preferably be sliced so as to maximize the amount of veneer, and minimize waste, taken from the desirable veneer-producing zone of the flitch.